The overall objective is to understand the neuroanatomical organization of areas of the nervous system responsible for the control of food and water intake and body weight regulation. The neuroanatomical organization of hypothalamic areas known to be related to feeding will be studied using cresyl violet and protargol staining for normal cells and fibers, Golgi impregnation for signal cell morphology and horseradish peroxidase to study afferent connections. The hypothalamic regions which will be studied include paraventricular, ventromedial, dorsomedial nuclei and lateral hypothalamic area. The above studies will use genetically obese Zucker rats (fa/fa) and their non-obese littermates as subject. In humans a relationship exists between obesity and certain diseases. Elucidation of the neuronanatomical pathways involved in the control of food intake and body weight regulation as well as demonstration of abnormalities in the brains of genetically obese animals will be of use in therapeutic approaches to obesity. Additional studies will determine the effect of diethylstilbestrol on hypothalamic structure in hamsters; this treatment can cause kidney and pituitary tumors, but knowledge of its neuronanatomical effects are limited.